In the production of sheets of paper or cardboard, a paper or cardboard web may be subdivided by transverse slitting and the like into a succession of sheets which are advanced along respective transport paths and may be stacked at the ends of these paths which can be provided with respective conveyors. In these systems, diverters are frequently provided to allow incoming sheets to be selectively fed along either of two outgoing paths formed by outgoing conveyors including an acute angle between them. The term "conveyor" is here used to refer to a belt system on which the sheets can travel, a surface against which a belt can hold a sheet while entraining it along the respective path, combination of belts, for example, between which the sheets can be displaced or any combination of the above.
The diverter thus can be provided between an incoming conveyor and two outgoing conveyors including an acute angle between them and usually including one or more conveyor belts, the outgoing conveyors generally leading to stacking stations, containers for the sheets or packaging stations in which the sheets can be wrapped or otherwise handled or processed.
German patent publication DE 29 22 135 A1 (corresponding to U.S. Pat. No. 4,195,539 issued 1 Apr. 1980) describes a sheet diverter for sheets of corrugated papers in which two skid-like guide elementa form a gate whose outlet opening is swingable back and forth between the two outgoing stretches. One of the guide elements is an electric guide element fixed on a swingable support to enable machining of the outlet opening to the position of the respective outgoing conveyor by a bending action. A more complex diverter for corrugated sheets is found in U.S. Pat. No. 3,831,929 in which a main path of travel lies in a horizontal plane and flaps are provided for diverting the sheets to either of a pair of secondary travel paths.
By and large, these systems are incapable of providing a problem-free diversion of sensitive sheets of light paper types (area weight&lt;80 g/m.sup.2), especially of short sheet lengths (&lt;1000 mm) at high speeds (&gt;200 m/min) and for wide machine widths (&gt;2200 mm). In such cases, a number of problems arise: firstly, the sheets must travel through a narrow gap between the guide surfaces and these surfaces must be flush with the surfaces onto which the sheets are delivered and gaps must be minimized so that the edges of the oncoming sheets do not catch.
Secondly, the guide elements must be sufficiently stiff that they do not vibrate or oscillate upon rapid switching since that can lead to jamming of the sheets in the slot formed between the guide elements.
Finally, for a rapid switchover at high sheet speed, the moment of inertia of the guide elements and the parts which move them must be held to a minimum. All of these requirements can only be satisfied to a limited extent with these earlier systems.